The subject-matter of the present invention is optical lenses, in particular ophthalmic lenses formed from a transparent organic polymer material with a high refractive index and a high Abbe number.
The term xe2x80x9coptical lenses with a high refractive indexxe2x80x9d means optical lenses with a refractive index of greater than or equal to 1.55 and preferably greater than 1.57.
Optical lenses according to the invention are preferably spectacle glasses.
Ophthalmic lenses with a high refractive index must have all the following characteristics:
a high transmission (transmission generally of greater than 85% and preferably of greater than or equal to 90%), with an absence of or optionally a very low light scattering,
a high Abbe number of greater than or equal to 30 and preferably of greater than or equal to 35, in order to avoid chromatic aberrations,
a low yellowing index and an absence of yellowing over time,
good impact strength (in particular according to the CEN and FDA standards),
good suitability for various treatments (shock-proof primer, anti-glare or hard coating deposition, and the like) and in particular good suitability for colouring,
a glass transition temperature value preferably of greater than or equal to 80xc2x0 C. and better still of greater than 80xc2x0 C., preferably of between 90 and 110xc2x0 C.
In addition, the polymerizable compositions for the manufacture of optical lenses must also be easy to process industrially.
In particular, it is desirable for the compositions to be able to be quickly polymerized, in particular photopolymerized, in order to reduce the cycle times in the manufacture of the lenses.
It has been found, according to the invention, that it is possible to obtain an optical lens made of transparent organic polymer material with a high refractive index and a high Abbe number by copolymerization of a mixture of monomers comprising at least one polythiol monomer and at least one monomer with a high Abbe number comprising two to four bridged cyclic end groups comprising an intracyclic ethylenic double bond or a linear or branched aliphatic residue comprising an ethylenic unsaturation, preferably a vinyl or ethylidene group bonded directly to a carbon of the ring.
The bridged cyclic end groups can be noncondensed or condensed cyclic groups.
It is recommended that the bridged cyclic end groups should be chosen from the groups of formulae: 
where n is an integer from 0 to 5 inclusive, k is an integer from 0 to 3 inclusive and j is an integer from 0 to 10 inclusive, and 
where n is an integer from 0 to 5 inclusive, kxe2x80x2 is an integer from 0 to 2 inclusive and jxe2x80x2 is an integer from 0 to 10 inclusive, Q represents a xe2x80x94C(Rxe2x80x2)2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NRxe2x80x2xe2x80x94 or xe2x80x94SO2xe2x80x94 group, with Rxe2x80x2 denoting H or a C1-C3 alkyl radical, preferably CH3, and R is a hydrogen atom or a C1-C3 alkyl radical, preferably CH3.
Mention may be made, among the recommended groups above, of groups of formulae 
in which Q represents xe2x80x94C(Rxe2x80x2)2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SO2xe2x80x94 or xe2x80x94NRxe2x80x2xe2x80x94, Rxe2x80x2 representing a hydrogen atom or a C1-C3 alkyl radical, preferably CH3, R is a hydrogen atom or a C1-C3 alkyl, preferably CH3, n=0 to 5 and m=0 to 8.
Preferably, Q represents the xe2x80x94CH2xe2x80x94 radical.
Preferably again, a monomer with a high Abbe number is chosen, the refractive index of which is at least 1.56.
Polythiol monomers which are suitable for the lenses according to the present invention are well known in the art and can be represented by the formula R1(SH)n1 in which n1 is an integer of 2 or more, preferably from 2 to 5, and R1 is an aliphatic, aromatic or heterocyclic radical.
The polythiol compound is preferably a dithiol, trithiol or tetrathiol compound, in particular a polythiol with a high Abbe number.
These polythiol compounds are well known in the art and are disclosed, inter alia, in Document EP 394,495.
Mention may be made, among dithiols of use in the present invention, of 9,10-anthracenedimethanethiol, 1,11-undecanedithiol, 4-ethylbenzene-1,3-dithiol, 1,2-ethanedithiol, 1,8-octanedithiol, 1,18-octadecanedithiol, 2,5-dichlorobenzene-1,3-dithiol, 1,3-(4-chlorophenyl)propane-2,2-dithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 1,4-cyclohexanedithiol, 1,1-cycloheptanedithiol, 1,1-cyclopentanedithiol, 4,8-dithiaundecane-1,11-dithiol, dithiopentaerythritol, dithiothreitol, 1,3-diphenylpropane-2,2-dithiol, 1,3-dihydroxy-2-propyl 2xe2x80x2,3xe2x80x2-dimercaptopropyl ether, 2,3-dihydroxypropyl 2xe2x80x2,3xe2x80x2-dimercaptopropyl ether, 2,6-dimethyloctane-2,6-dithiol, 2,6-dimethyloctane-3,7-dithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5-dimethylbenzene-1,3-dithiol, 3,3-dimethylbutane-2,2-dithiol, 2,2-dimethylpropane-1,3-dithiol, 1,3-di(4-methoxyphenyl)propane-2,2-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 10,11-dimercaptoundecanoic acid, 6,8-dimercaptooctanoic acid, 2,5-dimercapto-1,3,4-thiadiazole, 2,2xe2x80x2-dimercaptobiphenyl, 4,4xe2x80x2-dimercaptobiphenyl, 4,4xe2x80x2-dimercaptobibenzyl, 3,4-dimercaptobutanol, 3,4-dimercaptobutyl acetate, 2,3-dimercapto-1-propanol, 1,2-dimercapto-1,3-butanediol, 2,3-dimercaptopropionic acid, 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl 2xe2x80x2,3xe2x80x2-dimethoxypropyl ether, 3,4-thiophenedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 3,5,5-trimethylhexane-1,1-dithiol, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 2,6-naphthalenedithiol, 1,9-nonanedithiol, norbornene-2,3-dithiol, bis(2-mercaptoisopropyl)ether, bis(11-mercaptoundecyl)sulphide, bis(2-mercaptoethyl)ether, bis(2-mercaptoethyl)sulphide, bis(18-mercaptoctadecyl)sulphide, bis(8-mercaptooctyl)sulphide, bis(12-mercaptodecyl)sulphide, bis(9-mercaptononyl)sulphide, bis(4-mercaptobutyl)sulphide, bis(3-mercaptopropyl)ether, bis(3-mercaptopropyl)sulphide, bis(6-mercaptohexyl)sulphide, bis(7-mercaptoheptyl)sulphide, bis(5-mercaptopentyl)sulphide, 2,2-bis(mercaptomethyl)acetic acid, 1,1-bis(mercaptomethyl)cyclohexane, bis(mercaptomethyl)durene, phenylmethane-1,1-dithiol, 1,2-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 2,2-butanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,2-hexanedithiol, 1,6-hexanedithiol, 2,5-hexanedithiol, 1,7-heptanedithiol, 2,6-heptanedithiol, 1,5-pentanedithiol, 2,4-pentanedithiol, 3,3-pentanedithiol, 7,8-heptadecanedithiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 2-methylcyclohexane-1,1-dithiol, 2-methylbutane-2,3-dithiol, ethylene glycol dithioglycolate or ethylene glycol bis(3-mercaptopropionate). Mention may be made, among trithiols, of 1,2,3-propanetrithiol, 1,2,4-butanetrithiol, trimethylolpropane trithioglycolate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol trithioglycolate, pentaerythritol tris(3-mercaptopropionate), 1,3,5-benzenetrithiol and 2,4,6-mesitylenetrithiol.
Mention may also be made, among polythiols of use in the compositions of the present invention, of neopentanetetrathiol, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, pentaerythritol tetrakis(3-mercaptopropionate), 1,3,5-benzenetrithiol, 2,4,6-toluenetrithiol, 2,4,6-methylenetrithiol and polythiols corresponding to the formulae: 
(HSCH2CH2COOCH2)3CC2H5 (TMPT), and 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol.
Preferred polythiols according to the present invention are ethylene glycol bis(thioglycolate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(thiopropionate) (PETP), 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol (MDO) and bis(2-mercaptoethyl)sulphide (DMDS).
The polythiol component is generally present in the polymerizable compositions in a proportion of 5 to 60% by weight, preferably of 10 to 50% by weight and better still of 20 to 50% by weight with respect to the total weight of monomers present in the composition.
The second essential monomer constituent of the polymerizable compositions for the manufacture of the ophthalmic lenses according to the invention is a copolymerizable monomer with a high Abbe number comprising two to four end groups generally chosen from groups of formulae: 
preferably groups of formulae: 
in which Q, R, n, m, k, kxe2x80x2, j and jxe2x80x2 are defined as above.
The copolymerizable monomers with a high Abbe number comprising two or more bridged cyclic end groups which are preferred, as defined above, generally correspond to the formula:
Z"Parenopenst"A)naxe2x80x83xe2x80x83(I)
in which na is an integer from 2 to 4 and A is a radical chosen from radicals of formulae: 
in which Q represents xe2x80x94C(Rxe2x80x2)2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SO2xe2x80x94 and xe2x80x94NRxe2x80x2xe2x80x94, where Rxe2x80x2 represents H or a C1-C3 alkyl radical, preferably CH3, R represents H or a C1-C3 alkyl radical, preferably CH3, n=0-5 and m=0-8, and
(I) when na=2, Z represents a divalent radical of a formula: xe2x80x83xe2x80x94Sxe2x80x94Z2xe2x80x94Sxe2x80x94xe2x80x83xe2x80x83(III)
in which formulae X represents xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94, G and Gxe2x80x2 are "Parenopenst"Cnxe2x80x2H2nxe2x80x2O"Parenclosest"mxe2x80x2 groups, with nxe2x80x2=1 to 5, preferably nxe2x80x2=2, and mxe2x80x2 varies from 0 to 10, or a C1-C5 alkylene group, Z1 is chosen from divalent radicals of formulae: 
in which formulae Q is defined as above, B1 represents xe2x80x94C(R2)2xe2x80x94 or xe2x80x94Sxe2x80x94, R2 is a C1-C3 alkyl radical, preferably xe2x80x94CH3, x1=0 or 1, Y1 represents, independently of one another, Br, Cl or H, Y1 is an integer from 0 to 4, the Rb groups denote, independently of one another, a "Parenopenst"CH2"Parenclosest"q group, q is an integer from 1 to 4, preferably equal to 1 or 2, and p is an integer from 0 to 4, preferably from 0 to 2; and
Z2 is a divalent radical chosen from radicals of formulae: 
where Q, Rb and p are defined as above and Z3 is a divalent radical chosen from: 
where Q and x1 are defined as above;
(II) when na=3, Z represents a trivalent radical chosen from: 
where Rb and p are defined as above and Rc represents H or a C1-C3 alkyl group, preferably xe2x80x94CH3; and
(III) when na=4, Z represents a tetravalent radical chosen from the following radicals: 
where R3 is a C1-C5 alkylene radical or a 
radical where Rb and p are defined as above.
A first class of monomer constituents comprising bridged cyclic end groups coming within the scope of the above general formula (I) are monomers of formula: 
where R and X are defined as above, B is xe2x80x94Sxe2x80x94 or xe2x80x94C(CH3)2xe2x80x94, nxe2x80x2 and nxe2x80x3=1 to 5 and mxe2x80x2 and mxe2x80x3 vary from 0 to 10.
A recommended monomer of formula (IV) is the compound of formula: 
Monomers corresponding to the formula (IV), and the process for their preparation, are disclosed in Patent Document WO 88/02902.
Another recommended class of monomer constituents comprising two bridged cyclic end groups according to the invention are monomers of formula: 
where R=H or CH3, Rb is as defined above, preferably a propylene radical, pxe2x80x2 is an integer from 1 to 3, preferably equal to 2, and pxe2x80x3 is an integer equal to 0 or 1.
A recommended monomer of formula (V) is the monomer of formula: 
(MESDTMN) or mercaptoethyl sulphide dithiomethnorbornenecarboxylate.
These compounds of formula (V) are new.
Mention may be made, among monomers of formula (III) above, of monomers in which Z2 represents the following groups: 
Such monomers, and the process for their preparation, are disclosed in Patent Document JP-81 51360.
Mention may be made, among recommended trivalent monomer constituents comprising bridged cyclic end groups, of monomers of formulae: 
Compounds of this type, in particular tris(norbornenyl) isocyanurate, are disclosed in U.S. Pat. No. 5,182,360.
The monomer constituent or constituents comprising bridged cyclic end groups according to the invention are generally present in the polymerizable composition in a proportion of 10 to 70% by weight with respect to the total weight of the monomer constituents, preferably in a proportion of 20 to 70% by weight and better still in a proportion of 30 to 70% by weight.
Monomers of formula (II) in which X represents xe2x80x94Sxe2x80x94 are new products.
The polymerizable compositions according to the invention can also comprise other additional monomers which are copolymerizable with the above monomers, in particular thio(meth)acrylate monomers, such as monomers corresponding to the formula: 
in which:
R4 represents a linear or branched, monovalent or polyvalent, aliphatic hydrocarbonaceous radical or a monovalent or polyvalent, aromatic or heterocyclic group bonded directly to the sulphur atom of the thio(meth)acrylate group or groups by a nucleus or via a linear alkyl chain, it being possible for the R4 radical to comprise, in its chain, one or more groups chosen from xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or 
R5 represents hydrogen or xe2x80x94CH3; and
n2 is an integer from 1 to 6, preferably from 1 to 3.
Mention may be made, among monovalent R4 radicals, of linear or branched C1 to C5 alkyl radicals or radicals of formula: 
in which:
R6 and R7 are, independently of one another, H or a linear or branched C1-C5 alkyl radical;
R8 is a linear or branched C1-C5 alkyl radical, a C7-C10 aralkyl radical or a C6-C12 aryl radical which is optionally substituted, in particular by alkyl and/or halogen groups; and
n3 is an integer from 1 to 4.
Mention may be made, among preferred monovalent R4 radicals, of: 
Monomers of formula (VI) for which n2=1 and which are as defined above are disclosed, inter alia, in Patents U.S. Pat. No. 4,606,864, JP-63316766 and EP-A-0,384,725.
Mention may be made, among divalent R4 radicals coming within the context of the monomers of formula (VI), of linear or branched C2 to C10 alkylene radicals which can comprise, in their chain, one or more xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or 
groups, alkylidene radicals of formula 
in which R9 and R10 are C1-C5 alkyl radicals, radicals of formula: 
in which R11 and R12 are linear or branched C1-C5 alkylene groups which can comprise one or more xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or 
groups in their chains, Xxe2x80x3 is chosen from C1-C5 alkyl radicals and halogens, and n4 is an integer from 0 to 4, and radicals of formula: 
in which R13 and R14 are linear or branched C1 to C5 alkylene radicals which can comprise, in their chain, one or more xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or 
groups and t and s are equal to 0 or 1.
Mention may be made, among preferred divalent R4 radicals, of the following radicals: 
where qxe2x80x2 is an integer from 1 to 8; 
where X is xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94 and u is an integer from 1 to 4; 
where zxe2x80x2 is equal to 0 or 1 and uxe2x80x2, vxe2x80x2 and wxe2x80x2 are integers from 2 to 6; 
where uxe2x80x3 and vxe2x80x3 are integers from 1 to 4, 
Particularly preferred divalent R4 radicals are: 
and xe2x80x94C2H4xe2x80x94Sxe2x80x94C2H4xe2x80x94.
Divalent monomers of formula (VI) are disclosed, inter alia, in Patents EP-A-273,661, EP-A-273,710 and EP-A-384,725.
Mention may be made, among trivalent R4 radicals of the monomers of formula (VI), of C3 to C10 alkyltriyl radicals which can comprise, in their chain, one or more xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or 
groups, trivalent alkylaryl radicals, the alkyl chains of which comprise one or more xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94 groups, and trivalent aryl groups.
Mention may be made, among trivalent R4 radicals or R4 radicals with a higher valency, of: 
and the like.
Mention may be made, among monomers of formula (VI) recommended in the present invention, of: 
where R5 represents a hydrogen atom or a methyl group.
Very particularly recommended monomers in the present invention are bis(4-methacryloylthiophenyl)sulphide (BMTPS) and bis(2-methacryloylthioethyl)sulphide (BMTES).
Another class of thio(meth)acrylic monomers suitable in the compositions comprising monomers according to the invention corresponds to the formula: 
in which R5 represents H or CH3, R15 represents an optionally branched C2-C12 alkylene group, a C3-C12 cycloalkylene group, a C6-C14 arylene group or a C7-C26 alkarylene group, it being possible for the carbonaceous chain of the R15 group to be interrupted by one or more ether or thioether groups, and n5 is an integer from 1 to 6.
Such monomers are disclosed in U.S. Pat. No. 5,384,379.
These copolymerizable comonomers, when they are present, can represent from 10 to 60% by weight of the composition with respect to the total weight of monomers present, preferably 20 to 50% by weight.
The polymerizable compositions according to the invention can also comprise additives conventionally used in polymerizable compositions for the moulding of optical articles, in particular spectacle glasses, in conventional proportions, namely inhibitors, colorants, UV absorbers, fragrances, deodorants, antioxidants and anti-yellowing absorbents.
Mention may be made, as preferred examples of antioxidizing agents, of triphenylphosphine (TPP) and Irganox(copyright) 1010 (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CG1010).
Fragrances make it possible to mask the odour of the compositions, in particular during surface working operations.
The compositions according to the invention generally comprise polymerization initiators, preferably photoinitiators or mixtures of photoinitiators and of thermal initiators, in a proportion of 0.001 to 5% by weight with respect to the total weight of polymerizable monomers present in the composition.
Mention may in particular be made, among photoinitiators which can be used in the polymerizable compositions according to the invention, of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, alkylbenzoyl ethers, the photoinitiator sold by the Company Ciba-Geigy under the name CGI 1700, which is a 25/75 mixture of a compound of formula: 
and of a compound of formula: 
and the photoinitiator CGI 1850 sold by the Company Ciba-Geigy, which is a mixture (50/50) (by weight) of compound A and of Irgacure(copyright) 184 of formula: 
As indicated above, the preferred polymerizable compositions according to the invention are photopolymerizable compositions comprising one or more photoinitiators.
More preferably, the polymerizable compositions according to the invention are photo- and thermopolymerizable compositions comprising both a polymerization photoinitiator and a polymerization thermal initiator.
Thermal polymerization initiators are compounds which are well known in the art and mention may be made, among them, of peroxides, such as benzoyl peroxide, cyclohexyl peroxydicarbonate and isopropyl peroxydicarbonate.
Monomers of formula (I) can be synthesized either by a Diels-Alder reaction between a compound comprising two or more (meth)acrylate or thio(meth)acrylate functional groups and a cycloalkene, such as cyclopentadiene or norbornadiene, or by addition of thiol/ene type between a polythiol compound and an ene compound, such as cyclopentadiene, norbornadiene, vinylnorbornene or ethylidenenorbornene.
The polythiol compound and the ene compound are reacted in proportions corresponding substantially to one thiol group of the polythiol compound or compounds per mole of ene compound.
By way of example, the scheme is shown below for the synthesis of monomers with a high Abbe number according to the invention from 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene with a dithiol: 
where W is an aliphatic or aromatic radical.
In the following examples, except when otherwise indicated, all the parts and percentages are expressed by weight.
700 g of bisphenol A 2-ethoxylate diacrylate (EBPADA), Sartomer(copyright) SR 349, are introduced into a three-necked flask equipped with a mechanical stirrer, a dropping funnel for introducing reactant and a condenser. The EBPADA had a refractive index nD at 21xc2x0 C. at 1.5465 and a relative density of 21xc2x0 C. of 1.1478.
The acrylic monomer is then degassed by means of a roughing vacuum pump and then dinitrogen is introduced into the three-necked flask. 198 g of freshly cracked cyclopentadiene (CPD) are then added dropwise via the dropping funnel. The temperature of the reaction mixture rises as the Diels-Alder reaction between the cyclopentadiene and the diacrylate takes place. The excess cyclopentadiene is then discharged by alternating the vacuum by means of the roughing vacuum pump and the introduction of dinitrogen into the three-necked flask. Discharge of the excess cyclopentadiene is brought to completion by means of a rotary evaporator. If the presence of impurities is observed, the monomer obtained is then filtered by means of a vacuum flask.
The expected product, EBPADN, is obtained with a yield of 93.53%, this product having a molar mass of 556, a refractive index nD at 21xc2x0 C. of 1.5497 and a relative density at 21xc2x0 C. of 1.1569.
The synthesis is carried out as in the preceding synthetic example but without final discharge of the excess CPD by means of a rotary evaporator, in order to prevent the product from setting solid.
In this synthesis, use was made of 338 g of trimethylolpropane triacrylate, molar mass 296, refractive index nD at 21xc2x0 C. of 1.4752 and relative density at 21xc2x0 C. of 1.10067, which product is sold by the Company Cray Valley under the reference SR 351, and 217 g of cyclopentadiene were added.
The expected product, TMPTN, was obtained with a yield of greater than 95%, this product having a molar mass of 494, a refractive index nD at 21xc2x0 C. of 1.511 and a relative density at 21xc2x0 C. of 1.146.
The synthesis is carried as in the first synthetic example, using 211 g of bis[(2-methacryloylthio)ethyl]sulphide (BMTES); molar mass 282, nD at 21xc2x0 C. 1.5745, relative density 21xc2x0 C. 1.177, as starting material and 100 g of cyclopentadiene.
The expected product (MESDTMN) is obtained with a yield of greater than 95%, this product having a molar mass of 414, a refractive index nD at 21xc2x0 C. of 1.5683 and a relative density at 21xc2x0 C. of 1.1588.
It should be noted that the reactivity of a thiomethacrylate is much greater than that of the corresponding methacrylate (which would have required a catalyst of the Lewis acid type for the reaction).